TWI468535B - Method for inhibiting the diffusion of silicon by means of coarse aluminum crystals - Google Patents

Description

Coarse aluminum crystallization inhibiting enthalpy diffusion method

The invention relates to a coarse aluminum crystallization inhibiting enthalpy diffusion method, in particular to a heat exchange plate which can be applied to form an indoor cold air conditioner or a thin air conditioner radiator, which can not only make the flat tube body and the waveform heat constituting the heat exchange plate The fins are fastened and joined, and the welded portion can be subjected to a 90° bending deformation. The average crystal grain size of the flat tube body can be greater than 200 μm to suppress the occurrence of the bismuth diffusion phenomenon of the aluminum-lanthanum welding material.

Common techniques for joining metal materials and metal matrix composites include: fusion welding, brazing, diffusion bonding, and chemical bonding (adhesing); among them, chemical bonding Bonding is limited by the melting point of the binder and environmental aging problems, and cannot meet the high temperature use requirements or long-term outdoor exposure. The diffusion bonding requires a relatively high forward pressure on the joint interface due to the process, which is not applicable to the more complicated workpieces. And the effect of diffusion bonding is greatly affected by the surface state (smoothness, flatness, cleanliness, etc.), resulting in poor reliability after bonding; therefore, fusion welding and brazing become common metal materials and metal matrix composites. The main joining method; however, the fusion welding method often causes a clustering of the ceramic strengthening phase during the joining process, and the re-solidification process of the weld zone melting zone causes a large number of welding pores, and the ceramic strengthening phase gathers and the residual welding pores positive It is the most taboo material defect of metal matrix composite structural parts; for brazing technology, it can be applied not only to higher temperature and no environmental aging problems, but also because it does not need to apply positive pressure to the joint interface during the process. In the diffusion bonding method, the brazing technology is more suitable for the complex shapes and components commonly found in general engineering, and the reliability of the bonding steps, equipment and joints is better than diffusion bonding; in addition, since the soldering process only melts the solder. The base metal is basically kept in a solid state. Compared with the fusion welding technology, the material has no deterioration problem, especially when the metal matrix composite material is joined, the problem of the ceramic strengthening phase aggregation and the residual welding pores in the base material bead area does not occur.

Referring to Figure 12, a perspective view of a heat exchanger conventionally applied to a car, wherein the heat exchanger (2) is composed of a plurality of heat exchange plates (21), and each heat exchange plate (21) is The waveform heat dissipation fins (212) are sandwiched between the two flat tubes (211); as shown in the thirteenth figure, a partial cross-sectional view of the existing heat exchange plate before being heated, when the flat tube body (211) When bonding to the wave fins (212), the surface of the wave fins (212) is coated with an aluminum-bismuth solder material (22) so that the peaks and troughs of the wave fins (212) The welding material (22) can be temporarily bonded to the flat pipe body (211), and the heat exchange plate (2) can be brazed in the heating furnace to melt the welding material (22) and act on the solid-liquid interface. The wave-shaped heat sink fins (212) and the flat tube body (211) are tightly joined to each other; however, as shown in Fig. 14, during the heating process, the aluminum-bismuth solder material (22) may be due to gravity. Waves stacked on the wave fins (212) The junction between the valley or the trough and the flat tube (211) causes the aluminum-lanthanum welding material (22) to cause cracks or cracks in the joint due to the diffusion of the crucible in the solid-liquid phase coexisting region, so that the heat exchanger (the heat exchanger ( 2) After the use for a period of time, the refrigerant circulating in the flat pipe body (211) can be dissipated by the above cracks or gaps, which not only causes environmental hazards, but also has safety concerns.

Furthermore, the plurality of flat tubes constituting the heat exchanger for an automobile have side end faces on the same plane, and the heat exchanger is intended to be used for, for example, indoor air-conditioning or a thinner product, to minimize the overall space. And the purpose of not losing the refrigeration efficiency, the heat exchanger must be bent into an L shape or a U shape; however, the heat exchanger made by the above brazing has a relatively low bending rate, and the process rate is difficult to meet the actual production. Demand, so that the production capacity can not be improved, and even after bending, the heat exchanger often causes cracks in the weld.

Therefore, in view of the above-mentioned shortcomings, the present inventors have for many years of experience in rich design and development and actual production in the related industries, and have improved a heat exchange plate which can be applied to an indoor air conditioner or a relatively thin product, and not only a heat exchange plate. The flat tube body and the wave-shaped heat dissipating fin can be fastened, and the average crystal grain size of the flat tube body can be greater than 200 μm to suppress the occurrence of the bismuth diffusion phenomenon of the aluminum-lanthanum-based solder material; further, the method of the present invention The prepared heat exchange plate can be bent into an L shape or a U shape at a bending rate of 12 to 30 degrees per second, and has a better process rate to meet actual production requirements.

In order to achieve the above-described implementation objectives, the inventors have developed the following implementation techniques, First, the aluminum material is extruded into a flat tube body, and the extrusion temperature is a low temperature between 350 and 480 degrees Celsius, thereby improving the material storage energy, and the average crystal grain size of the flat tube body is between 30 and 100 μm. The flat tube body may not include a hot-dip galvanizing treatment step; then, the wave-shaped heat-dissipating fins are sandwiched between the two flat tubes to form a heat exchange plate, wherein the wave-shaped heat-dissipating fins are coated with aluminum- The welding material of the tantalum system; finally, the heat exchange plate is brazed and sintered, the sintering temperature is higher than 590 degrees Celsius, preferably between 590 and 630 degrees Celsius, and the sintering time is more than 30 minutes, preferably 30 Between ~60 minutes, the joint between the flat tube and the wave-shaped fins is welded, and the high-temperature welding process induces coarse grain growth, so that the average grain size of the flat tube can be greater than 200 μm; Therefore, the aluminum-lanthanum-based solder material deposited on the junction between the troughs or troughs of the wave-shaped heat-dissipating fins and the flat tube body during welding can be suppressed, and the average depth of the helium diffusion is preferably not more than 40μm to solve the traditional cause The diffusion causes the refrigerant flowing in the flat tube to pass through the crack or gap of the weld when the heat exchanger is used.

In an embodiment of the invention, the wave-shaped heat sink fins may be bonded to one or both sides of the 3003 heart material in the AA specification developed by the American Aluminum Association.

In an embodiment of the present invention, the inside of the flat pipe body is provided with a plurality of holes penetrating the flat pipe body along the extrusion direction, and the holes are preferably independent and parallel, thereby increasing the pressure resistance of the flat pipe body and For the circulation of refrigerant.

Further, the method of suppressing the ruthenium diffusion method by the coarse aluminum crystal of the present invention The heat exchange plate can be bent at a bending rate of 12 to 30 degrees per second, has a better process rate to meet actual production requirements, and the heat exchange plate can be bent into, for example, an L shape or a U shape, so that the present invention is made The heat exchanger can be applied to, for example, an indoor air conditioner or a thinner air conditioner radiator.

The object of the present invention and its structural and functional advantages will be explained in conjunction with the specific embodiments according to the structure shown in the following drawings, so that the reviewing committee can have a more in-depth and specific understanding of the present invention.

First, please refer to the first and second figures, respectively, which are respectively a flow chart of a preferred embodiment of the coarse aluminum crystallization suppressing enthalpy diffusion method of the present invention, and a partial cross-sectional view of the heat exchange plate applicable to the method of the present invention. The system includes the following steps: Step 1 (S1): extruding the aluminum material into a flat tube body (111), and the extrusion temperature is between 350 and 480 degrees Celsius, so that the average crystal grain size of the flat tube body (111) is obtained. The range is between 30 and 100 μm; wherein the flat tube body (111) may not include a hot-dip galvanizing treatment step, and in order to improve the pressure resistance of the flat tube body (111) and increase the flowability of the refrigerant, the flat tube may be used. The inside of the body (111) is provided with a plurality of holes (113) penetrating the flat tube body (111) along the extrusion direction, and the holes (113) are preferably independent and parallel, thereby forming a harmonica tube structure; Step 2 (S2) The waveform heat dissipation fins (112) are sandwiched between the two flat tube bodies (111) to form a heat exchange plate (11), wherein the wave shape heat dissipation fins (112) are coated with aluminum-bismuth welding. Material (12); and The wave-shaped heat dissipation fins (112) may be, for example, bonded to the 4343 alloy by one or both sides of the 3003 core material, and the above model is an AA specification by the Aluminium Association; and the third step (S3): The heat exchange plate (11) is subjected to brazing sintering, and the sintering temperature is higher than 590 degrees Celsius, preferably between 590 and 630 degrees Celsius, and the sintering time is more than 30 minutes, preferably between 30 and 60 minutes. The fusion between the flat tube body (111) and the wave-shaped heat dissipation fins (112) is achieved, and the average crystal grain size of the flat tube body (111) is greater than 200 μm; it is noted that the brazing sintering can also be, for example, Conventional electric furnace heating, gas heating method or high-frequency nitrogen addition treatment, because the sintering furnace can control the tempering time, the expansion coefficient is small, so that the crystal phase of the weld is relatively stable, so it is a preferred embodiment.

Next, the scope of the process of the present invention can be further proved by the following specific embodiments, but it is not intended to limit the scope of the invention in any form: first, the aluminum material is extruded at a low temperature of about 350 degrees Celsius. Press-formed into a flat tube body (111) such that the average crystal grain size of the flat tube body (111) ranges from about 59.8 μm, as shown in the third figure, which is a flat shape in which the brazing step is not performed in the specific embodiment of the present invention. a photomicrograph of the tube body grain size; next, the wave-shaped heat sink fins (112) coated with the aluminum-lanthanum-based solder material (12) are sandwiched between the two flat tubes (111); The furnace is fired at a high temperature between 590 and 630 degrees Celsius and between 30 and 60 minutes. The result of the soldering is as shown in the following table; please refer to the fourth figure together, the micrograph of the flat tube grain size after the hard soldering step of the embodiment of the present invention is performed at 610 ° C / 45 minutes, which can be clearly seen. The flat tube body (111) has an average crystal grain size of about 200 μm.

In addition, since the flat tube body (111) of the present invention improves the material storage energy through the low temperature (350-480) extrusion type, and then is grown by high temperature (590 to 630 degrees) for coarse grain growth, so as to be deposited on the wave fins. The aluminum-antimony consumable (12) at the junction between the trough or trough of the sheet (112) and the flat tube (111) (please refer to the second figure) can be suppressed. Please refer to the fifth figure, which is a photomicrograph of the heat exchange plate made of 610 ° C / 45 minutes sintering environment, where the diffusion of the weld is suppressed, and the left picture is a partial enlarged view of the right figure, left As is clear from the figure, the thickness of the eutectic lanthanum is about 100 μm, the 矽 diffusion to the flat tube body (111) is about 31 μm deep, and the average enthalpy diffusion depth is not more than 40 μm; therefore, the coarse aluminum crystal of the present invention suppresses 矽The diffusion method can solve the problem that the conventional aluminum-lanthanum welding material (12) causes the air-conditioning radiator (1) to be used in the flat tube body (111) due to the diffusion of the air-conditioning radiator (1). Or the problem of gap escaping occurs.

Furthermore, the heat exchange plate (11) formed by the method of the present invention can be bent at a bending rate of 12 to 30 degrees/second due to the improvement of the diffusion of the crucible to the flat tube body (111), which is preferable. The process rate is adapted to the actual production demand, and the heat exchange plate (11) can be bent into an L shape or a U shape, and a thinned air conditioner heat dissipation is formed by a plurality of bent heat exchange plates (11). (1), as shown in the sixth figure, is a schematic view of the three-dimensional appearance of the air conditioner heat sink made by the method of the present invention; the following table shows the high temperature between 590 and 630 degrees Celsius, and between 30 and 60 minutes The bending time of the heat exchange plate (11) obtained by sintering is performed. The "X" in the table refers to the case where the bending process is not performed because of the inability to weld; the sintering environment of 610 ° C / 45 minutes is known from the table. It can be successfully soldered, and the solder joints spread only to the surface grain boundary of the wave fins (112). When bending, only a small part of the material is peeled off (as shown in the seventh figure), and the joints (welds) The tensile strength is greater than 20 MPa, wherein the right image of the seventh figure has two dotted circles, wherein the left circle The magnified view is the left image of the seventh figure, and the circle on the right clearly shows that only a small part of the material is peeled off during bending, and the welding performance is still maintained; while the sintering environment at 610 ° C / 60 minutes can be successfully welded. Then, it has spread to the flat tube body (111) (as shown in the eighth figure), which may cause the flat tube body (111) to rupture during bending, resulting in poor product. Similarly, in the right picture of the eighth figure, there are two A dotted circle, in which the partial enlargement of the left circle is the left image of the eighth figure, and the right circle clearly shows that the 矽 diffuses to the flat pipe; further, 630 ° C / The 30-minute sintering environment can be successfully welded, the welding area is narrow, and part of the position is peeled off (as shown in Figure 9), and the tensile strength of the joint (weld) can be greater than 20 MPa; 630 ° C / 45 minutes of sintering environment Although it can be successfully welded, the welded part has multiple positions to be peeled off, and the peeling hole can be observed at the position of the flat tube body (111) under the welding point (as shown in the tenth figure), and the flat tube body is easily caused when bending ( 111) rupture, resulting in low product yield; and the resulting 630 ° C / 60 minute sintering environment (as shown in Figure 11) is similar to 610 ° C / 60 minutes.

It can be seen from the above description that the present invention has the following advantages compared with the prior art:

1. The coarse aluminum crystallization inhibiting enthalpy diffusion method of the present invention increases the storage energy of the flat harmonica tube body by low temperature extrusion, and then induces coarse grain growth by high temperature welding, so that the average crystal grain size range of the flat tube body can be larger than 200μm, to further solve the problem of the diffusion of the bismuth during the brazing of the aluminum-lanthanum welding consumables The conventional aluminum-lanthanum-based welding material causes the problem that the refrigerant flowing in the flat tube body is dissipated by the weld crack or gap due to the diffusion of the crucible.

2. The heat exchange plate produced by the method of the invention can be bent into an L shape or a U shape at a bending rate of 12 to 30 degrees/second, and has a better process rate to meet actual production requirements, so that the invention is made. The heat exchanger can be applied to, for example, indoor air-conditioning or a thinner product.

In summary, the coarse aluminum crystallization inhibiting enthalpy diffusion method of the present invention can achieve the intended use efficiency by the above-disclosed embodiments, and the present invention has not been disclosed before the application, and has completely complied with the patent law. Regulations and requirements.爰Issuing an application for a patent for invention in accordance with the law, and asking for a review, and granting a patent, is truly sensible.

The illustrations and descriptions of the present invention are merely preferred embodiments of the present invention, and are not intended to limit the scope of the present invention; those skilled in the art, which are characterized by the scope of the present invention, Equivalent variations or modifications are considered to be within the scope of the design of the invention.

<this invention>

(1)‧‧‧Air conditioner radiator

(11) ‧‧‧Heat Exchange Board

(111)‧‧‧flat tube

(112)‧‧‧ Waveform fins

(113)‧‧‧ holes

(12)‧‧‧welding materials

(S1)‧‧‧Step one

(S2)‧‧‧Step 2

(S3) ‧ ‧ Step 3

<existing>

(2) ‧ ‧ heat exchangers

(21) ‧‧‧Heat Exchange Board

(211)‧‧‧flat tube

(212)‧‧‧ Waveform fins

(22)‧‧‧welding materials

First Figure: Flowchart of the steps of a preferred embodiment of the present invention

Figure 2 is a partial cross-sectional view showing the heat exchange plate of the air conditioner heat sink according to the preferred embodiment of the present invention during heat treatment

Third: a micrograph of a flat tube crystallite size of a specific embodiment of the present invention without a brazing and sintering step

Fourth: Microscopic photograph of the grain size of the flat tube after the brazing and sintering step in the specific embodiment of the present invention

Fig. 5 is a photomicrograph showing the suppression of the diffusion of the weld at the weld in the specific embodiment of the present invention

Figure 6: Schematic diagram of the three-dimensional appearance of the air conditioner radiator made by the method of the present invention

Figure 7: Micrograph photograph of the heat exchange plate made by the present invention in a sintering environment at 610 ° C / 45 minutes in the joint between the flat tube and the wave fins

Figure 8: Photomicrograph of the heat exchange plate made in the sintering environment of 610 ° C / 60 minutes of the present invention at the junction of the flat tube and the wave-shaped fins

Ninth Photograph: Micrograph of the heat exchange plate made in the sintering environment of 630 ° C / 30 minutes of the present invention at the junction of the flat tube and the wave-shaped fins

Figure 10: Micrograph of the heat exchange plate made in the sintering environment of 630 ° C / 45 minutes of the present invention at the junction of the flat tube and the wave-shaped fins

Figure 11: Photomicrograph of the heat exchange plate made in the sintering environment of 630 ° C / 60 minutes of the present invention at the junction of the flat tube and the wave-shaped fins

Twelfth Figure: Stereoscopic view of the heat exchanger traditionally applied to automobiles

Figure 13: Schematic diagram of a partial cross section of a conventional heat exchange plate before it is heated

Figure 14: Schematic diagram of a partial cross section of a conventional heat exchange plate when heated

(S1)‧‧‧Step one

(S2)‧‧‧Step 2

(S3) ‧ ‧ Step 3

Claims (8)

A coarse aluminum crystallization inhibiting enthalpy diffusion method is applied to a heat exchange plate, and the method comprises the following steps: Step 1: extruding an aluminum material into a flat tube body, and the extrusion temperature is between 350 and 480 degrees Celsius. The average crystal grain size of the flat tube body ranges from 30 to 100 μm; step two: sandwiching the wave shape heat dissipation fins between the two flat tube bodies to form the heat exchange plate, wherein the waveform heat dissipation The fin system is coated with an aluminum-lanthanum welding material; and step 3: the heat exchange plate is subjected to brazing sintering at a temperature of about 610 degrees Celsius, a time of about 45 minutes or about 630 degrees Celsius, and a time of about 30 minutes. Under the condition, the joint between the flat tube body and the wave-shaped heat dissipation fin is achieved, and the average crystal grain size of the flat tube body is greater than 200 μm. The coarse aluminum crystallization inhibiting enthalpy diffusion method according to claim 1, wherein the aluminum-lanthanum-based solder material has a mean diffusion depth of not more than 40 μm. The coarse aluminum crystallization inhibiting enthalpy diffusion method according to claim 1, wherein the wave-shaped heat-dissipating fin is one of the 3003 heart material or the double-sided joint 4343 alloy in the AA specification established by the American Aluminum Association. The coarse aluminum crystallization inhibiting enthalpy diffusion method according to claim 1, wherein the flat tube body is provided with a plurality of holes penetrating the flat tube body along the extrusion direction. A coarse aluminum crystallization inhibiting enthalpy diffusion method as described in claim 4, wherein the pores are independent and parallel. The coarse aluminum crystallization inhibiting enthalpy diffusion method according to claim 1, wherein the heat exchange plate formed by the method can be bent at a bending rate of 12 to 30 degrees/second. The coarse aluminum crystallization inhibiting enthalpy diffusion method according to claim 6, wherein the heat exchange plate is bent into an L shape or a U shape. The coarse aluminum crystallization inhibiting enthalpy diffusion method according to claim 6 or 7, wherein a plurality of bent heat exchange plates are used to manufacture an air conditioner heat sink.